Power cylinder assembly



Dec. 22, 1959 M. J. LlEsER POWER CYLINDER ASSEMBLY Filed Dec. l5, 1954 INV NToR:

sembly away from the cylinder extension member. ditional objects and advantages will appear as the specid 2,913,040 POWER CYLINDER ASSEMBLY Mathias J. Lieser, Chicago, lll., assignorV to MeadV Spe- 'cialties Company, Chicago, Ill., a corporation of Illinois `Application December. 15, 1954, Serial No..475,387

' 1 Claim. `(Cl. 121-38) AThis invention relates to a power cylinderassembly, and is especially concerned with' an assembly of this character wherein the application of pressure uid against a piston or ram is operative to move the same through a stroke of predetermined length.

Frequently a power cylinder assembly having an adjustable stroke length would be desirable for then the user of such device could tailor the operation to meet their specific needs. Particularly would this be true if the devices had infinitely variable stroke lentghs within some predetermined limits. On the other hand, power cylinder assemblies with adjustable stroke lengths would not be acceptable if the over-all lengths thereof were greatly in excess of the length actually required to provide a stroke of any given length. Ordinarily, stroke lengths might be decreased from some `predetermined maximum but without decreasing the casing length which -would then lbe excessive. To provide a variable stroke length power cylinder, and at the same time provide a cylinder length which is never greater than that actually required to provide any selected stroke length, has long been a problem in the art.

Itis, accordingly, an object of this invention to provide a solution to the problem set forth above that has long existedin this lield. Another object is to provide a power cylinder having an infinitely variable stroke length, and in which the unit at no time has a length ngreater than that necessary to accommodate thevstroke of any selected length. Still another object is in the provision of a power cylinder having a ram assembly mounted for reciprocable movement therein, the cylinder having an open end telescopically engaging a cylinder ex- `tension memberaxially adjustable relative to the cylin- Vder---the stroke length of the ram assembly being determined by the position of the extension member, whereby the stroke length can be determined through adjustment "of the cylinder extension.

A further object is to provide a structure asY described in which the extension member provides a closure for the cylinder and has an elongated recess extending axially therein that provides a seat for a biasing spring and that receives the biasing spring therein during its compression, the biasing spring serving to normally urge the ram asication proceeds.

An embodiment of the invention is illustrated in the accompanying drawing, in which:

Figure l is a top plan view of the cylinder assembly;

Figure 2 is an end view in elevation of the assembly with an adjustment wrench being shown in phantom; and Figure 3 is a longitudinal sectional view taken on the line 3-3 of Figure l.

The assembly is designated in the drawing generally with the letter A and, as is seen best in Figure 3, comprises an elongated cylinder or casing having a longitudinally extending bore ll therethrough. At one end the cylinder 10 is externally threaded as shown at 12, and

y United States Patent O Fice md 22,1959

2 a closure cap 13 is threadedly mounted upon that end of the cylinder. `The closure collar 13 is provided with an inlet port14 in open communication with the bore 11, and is adapted to be connected to a source of fluid Aunder pressure.

The opposite end of the cylinder 1t) is equipped with external threads 15 that threadedly receive thereon a collar 16 having an inwardly extending top wall 17 provided with internal threads 18. Telescopically received within the cylinderv10 is a stroke adjustor member or cylinder extension member 19 that is freely movable axially within the bore 11, and Vthat is provided with external threads 20 that are adapted to threadedly engage the j equipped with an inwardly extending bearing wall portion 23 that is in parallel spaced-apart relation with the outer kwall of the extension member 19. The end wall 22 of the extension member has a pair of spaced openings 24 extending therethrough that provide vents or exhaust ports for the bore 11, and also provide wrench Openings adapted to receivea spanner wrench 25 therein, as shown in Figure 2.

The bearing wall 23 of the cylinder extension member Vdefines Aan elongated, annular passage therethrough that {slidably receives the stem or shaft 26 of a ram assembly that comprises also a piston 27 that is rigidly secured to the stem. The piston may be secured to the stem by any suitable means, and in the specific illustration given the inner end of the stem is reduced in diameter and the piston 27 is swaged onto that end of the stem.

The outer wall of the extension member 18 and the inner Wall 23v define therebetween a recess or chamber 28 that is, elongated and extends substantially the entire length of the extension member. The recess 28 at one end thereof provides a seat for an elongated coil spring 29, that at its opposite end seats within a liner or spring seat member`30 that is mounted upon a shaft 26,and

that isin contiguous relation with the piston 27 on one side thereof. vThe spring 29 functions to bias the piston 27 away from the extension member 19 and toward the uport'14 that communicates with the bore 11. To provide a sealingrelation between the walls of the bore and the 'piston 27, a piston cup or seal member 32 is mounted for reciprocation within the bore 11. The member 32 ,conformsin shape to thevcontiguration of the bore .11

and, in the illustration set forth in the drawings, that coniiguration is circular. The cup or seal 32 is provided with an outwardly extending boss 33 that is centrally oriented and that is adapted to abut the end wall of the closure cap 13, and to provide a seal about the port 14. The cup 32 is provided with an outwardly flared ange 34 that sealingly engages the walls of the bore 11. The cup or seal 32 may be formed of any suitable material, such as rubber or leather or various synthetics, all as is well known in the art.

Preferably, a seal or O-ring 35 is provided between the closure cap 13 and the casing or cylinder 10 so as t0 prevent the escape of pressure iluid from that end of the cylinder. If desired, the casing or cylinder 10 may be equipped adjacent the opposite ends thereof with laterally extending ears or flanges 36, each of which has an opening 37 therethrough that can be used in rigidly mounting the unit to suitable support members.

Operation l receptacle 28 provided within the cylinder extension member v19. The stroke length of the ram assembly is limited by the position of the cylinder extension member V19, for ultimately in its movement the piston 27 will engage the inner end of the extension member. To bring about reverse movement of the ram assembly, the bore 11 is simply evacuated through the port 14 and the spring 29 will be operative to return the ram assembly to its initial position which is shown in Figure 3. It is customary to provide cylinders which are somewhat longer than necessary for room must be provided in each cylinder to permit the maximum stroke length desired, and at the same time permit complete compression of the biasing spring. In the arrangement l have provided, the closure member 19 is equipped with a recess or chamber that accepts the compressed spring therein and, therefore, the cylinder need not have an excessive length in order to afford the desired stroke length.

This feature of the closure member is not achieved through a decrease in the area of the bearing member that slidably receives the stem 26 of the ram assembly. As is well known, there is considerable tendency for the Vstem to twist or to be canted within the bearing, and as a result a long bearing surface is desired for it is effective to stabilize or to conne the stem and thereby cause reciprocatory movement of the ram assembly along the true longitudinal axis of the cylinder. It is apparent from Figure 3 that the bearing wall 23 of the closure member is elongated and provides a long bearing area.

The stroke length of the ram assembly is infinitely variable, and this variable stroke length is provided without having a cylinder that is longer than necessary to provide any selected stroke length. That is to say, both the cylinder length and stroke length are variable together so that the cylinder length never unnecessarily exceeds the stroke length of the assembly. This is desirable for it results in a universal type of power cylinder assembly which is dimensionally small when short stroke lengths are required, and that is increased in length only when the stroke length is increased and only to the extent that the stroke length is increased.

It will be noted in Figure l that three different stroke lengths are indicated. I have found that the stroke length can be varied between one to three inches, for example, with the structure I provide without substantially increasing the over-all length of the assembly when the shortest stroke length is used. Through a single cylinder extension member, a power cylinder assembly is provided that has an adjustable stroke length, that has a closure cap equipped to receive the compressed biasing spring therein and that provides an elongated bearing that stabilizes and confines the movement of the ram assembly along the true longitudinal axis of the cylinder.

While in the foregoing specication an embodiment of the invention has been set forth in considerable detail for purposes of illustration, it will be apparent to those skilled in the art that numerous changes may be made in those details without departing from the spirit and principles of the invention.

I. claim:

In a power cylinder assembly, an elongated cylinder open at one end and having a piston mounted for reciprocatory movement therein, port means at the other end of said cylinder for introducing pressurized uid into said cylinder, means on said piston establishing a fluid seal between said piston and the interior wall of said cylinder, said piston being equipped with an elongated stem extending axially of said cylinder in the direction of said open end, the outer wall of said cylinder adjacent said one end being threaded, a collar threadably carried on the threaded portion of said cylinder, said collar having an inwardly extending annular ange equipped with internal threads, said annular ange being positioned adjacent the said one end of said cylinder, and an externally threaded cup-shaped cylinder extension member telescopically received in said cylinder at the open end thereof and threadably carried by said annular flange, said cylinder extension member having an axially inwardlyextending annular bearing wall therein and equipped with an elongated opening therethrough slidably receiving said stem with said stem extending outwardly of said member, the said bearing wall and the side wall of said cup-shaped extension member cooperating to dene an annular space, an exhaust opening in the end wall of said cup-shaped member communicating with said annular space, and a coil spring mounted in said space and extending between said end wall and said piston, said opening providing a tool-receiving means for rotating said memberto alter the stroke of said piston.

References Cited in the file of this patent UNITED STATES PATENTS 631,698 Cowles Aug. 22, 1899 640,767 Hollman Jan. 9, 1900 680,989 Thoele Aug. 20, 1901 1,103,020 Austin July 14, 1914 1,817,352 Cordell Aug. 4, 1931 1,858,342 Rollman May 17, 1932 1,863,448 Landenberger et al June 14, 1932 1,901,900 Daux Mar. 2l, 1933 2,235,617 Klinzing Mar. 18, 1941 2,408,233 Smith Sept. 24, 1946 2,733,691 Johnson Feb. 7, 1956 FOREIGN PATENTS 531,883 Great Britain Ian. 31, 1941 

